1. Field of the Invention
The invention relates to shaped bodies.
2. Background Art
Shaped bodies, such as casting molds for the confectionary/patisserie industry, food molds, for example for shaping butter, chocolate, chocolate candies and ice cream, baking molds and baking sheets, all in general called baking molds below, even if not explicitly used for baking, are well known and are generally produced from aluminum, cast iron, clay, porcelain or glass. The use of such baking molds has the considerable disadvantage that removing the foods, called baked goods below, from the baking mold is difficult, since the baking molds are rigid and immovable.
As an improvement, therefore, in some cases complicated baking molds have been developed which need to be opened via a mechanism, thus facilitating removal of the baked goods. Such molds are not optimal, however, since firstly a complicated mechanism is necessary, and secondly only very specific geometries of the baking molds are possible. EP 0 992 195 B1 describes the use of silicone which is obtained by a platinum crosslinking process for producing patisserie molds and baking sheets. Advantages with respect to the abovementioned baking molds with this process are that the silicone is elastic and thus the baked good may be removed very easily from the baking mold, especially since the adhesion of the baked good to the silicone baking mold is extremely low, due to the nature of the silicone. Other advantages are that the silicone is inert toward foods and is considered to be physiologically harmless. Furthermore, silicone can be washed readily and has good physical and chemical resistance to oxygen, UV radiation and ozone. The same advantages also apply to food molds in general, for instance for shaping butter, chocolate/chocolate candies and ice cream, where, in addition, the advantage of the cold flexibility of silicone elastomers becomes important.
Disadvantages of silicones which are crosslinked by platinum are the yellow and/or brown discoloration of the crosslinked silicones which are visible, in particular, in the case of high-volume silicone pieces. The discolorations are caused by the platinum which, at the end of the crosslinking, is present as platinum colloid, as described in J. Am. Chem. Soc. 108 (1986) 7228ff. Furthermore, in many platinum-crosslinked silicones, transparency is decreased and the silicone elastomers are thus not transparent, but cloudy or “translucent.”
The platinum catalysts have the further disadvantage that silicone rubbers which contain them have, after all the essential constituents have been mixed, only a limited processing time, since crosslinking proceeds even at room temperature. Although the processing time of the compositions may be increased by incorporating substances which inhibit the activity of the platinum catalyst (“inhibitors”), their use in turn reduces the curing rate of the composition.
It would be desirable to provide shaped bodies of addition-crosslinking silicones which do not have the abovementioned disadvantages.